I had signed a lease with my then girlfriend for a June to June rent. It was a two person apartment in Ohio. Me and my ex decided to have a third roommate move in to help lessen the total amount of rent. So we made an agreement to pay a third of the rent each. We all started paying a third of the rent starting in June, including the security deposit. 6 months into the lease my ex decided to move out without notice to me or the landlord. I then found out that she decided to pay three months half rent to the landlord before she left. At this point I am suing her for half of the rent for the remaining four months plus the security deposit (I paid her third of the security deposit).
I have not tried to find another roommate to replace her as well as the other roommate that is not on the lease, still lives here. She tried to find another roommate to move in with me but I refused because I don't want anyone living with us that I don't know. I don't think she has any proof of this because it was done orally.
Will I win?
I also want to point out that since we were both under 21 when we signed the lease, my grandmother cosigned for both of us.

